Dynamic Responses and Nonlinear Characteristics of a Nonlinear Absorber with Euler-Buckled Beams for Spacecraft Flywheel Systems

Abstract

In order to effectively mitigate the micro-vibration energy from the on-orbit flywheel and high-level vibration transmitted to flywheel system in the launching stage, a nonlinear vibration absorber (NVA) with Euler-buckled beams is developed and investigated in this paper. The NVA is composed of a linear supporting spring and a set of parallel Euler-buckled beams which is used as a negative stiffness corrector. In order to evaluate vibration reduction performance and stability characteristics of this developed nonlinear coupled dynamic system with NVA. First of all, a multi-degree-of-freedom compound dynamic model, including the flywheel system, the NVA and the supporting structural plate in the satellite platform, is built. Then, based on the systematic dynamic equations, the approximate steady-state solutions are derived by using the complexification-averaging (CX-A) method under on-orbit and launching loads, respectively. The analytical method and solutions are validated by using the numerical method. The proposed NVA can realize excellent vibration mitigation performance for the three-degree-of-freedom (3-DOF) coupled nonlinear system under the launching and on-orbit excitations. Next, the slow-variable manifold equation is analyzed to address the dynamic bifurcation behaviors of the nonlinear compound system and the influences of the excitation amplitude on the bifurcation characteristics are focused on. The results show that a 3-DOF system is more prone to instability and requires larger external excitation to escape the instability region. The calculation results also show that the stiffness ratio and excitation amplitude have significant effects on the bifurcation characteristics, and a proper stiffness ratio can be chosen to avoid bifurcations. Finally, compared with typical pure cubic stiffness NVA, the proposed NVA exhibits greater adaptability, and can work efficiently for a relatively larger range of excitation amplitude.